Catalytic conversion



Patented Dec. 14, 1943 ,smi

CATALYTIC CONVERSION No Drawing. Original application September 22, 1942, Serial No. 459,326. Divided and this ap-. plication May 5, 1943, Serial No. 485,946

(Cl. Mil-683.4)

12 Claims.

This invention relates to improved catalytic conversions executed with the aid of aluminum halide-containing catalysts.

The aluminum halides are known to possess the ability to catalyze a great number of chemical reactions. Because of its availability and relatively low cost, the use of the chloride is generally preferred. Many of the aluminum chloride catalysts utilized heretofore, however, possess distinct disadvantages which often render their use on a practical scale diflicult, if not impossible. Aluminum chlorideeither per se or supported upon a support material generally does not permit the attainment of the degree of contact between catalyst and material being treated required to obtain the most eflicient results. This is particularly so when operating in the liquid phase; and many processes, such as, for example, the treatment or conversion of hydrocarbons, are often'efiected more advantageouslyin the liquid phase. A further disadvantage often inherent in the use of solid aluminum chloride catalysts resides in the difflculty with which a desired catalyst bed temperature can be effectively maintained, due to the poor heat conductivity of most of these catalysts. Since a considerable portion of these solid catalysts often consists of the inert support material, a relatively large reaction zone is generally needed for relatively small amounts of the active catalyst constituent.

The use of aluminum chloride in the molten state is entirely unsatisfactory because of its high melting point and relatively high volatility. Modified forms of aluminum chloride catalysts comprising, for example, aluminum chloride in admixture with other halide salts have been proposed. Certain of these mixtures possess melting points which are appreciably lower than that of aluminum chloride. However, such mixed catalysts, when used in the compositions at which they possess desirable catalytic activity generally still possess melting points which are sufficiently high not only to prevent their efficient use in reactions which must be conducted at relatively low temperatures, but to entail serious difiiculties in moving the catalysts in their molten form through the system. To avoid the latter diificulty means must be resorted to, such as, for example, the heating or elaborate lagging of pipes to prevent the freezing of any part of the catalyst therein. Sludge-type catalysts, such as organic aluminum chloride complexes, have a relatively limited field of application and these also present serious difficulties not only in the handling of these materials within the system,

but in their separation from the product. The complex catalysts generally become quite viscous at low temperatureaoften approaching the consistency of a paste at temperatures of, for example, about 20 0., thereby rendering extremely difilcult the movement of the catalysts within the system and also making difilcult, if not impossible, the obtaining of a proper degree of contact between the catalyst and the mate-.

rial being treated, Slight amounts of impurities in the charge, furthermore, aid in quickly increasing the viscosity of such sludge-type catalysts at the lower temperatures to a point where the duration of the operation is far below that permissible in a practical operation. It is, therefore, readily apparent that aluminum halidecontaining catalysts of high activity which are able to maintain their fluidity and activity at relatively low temperatures in the absence of the above-described diihculties are highly desired.

It is an object of the present invention to provide an improved process for the more eflicient execution of catalytic reactions in the liquid phase in the presence of fluid catalysts comprising an aluminum halide.

Another object of the invention is the provision of an improved process for the more eflicient treatment of hydrocarbons in the liquid phase with the aid of fluid aluminum chloride-containing catalysts. Other objects and advantages of the invention will become apparent from the following detailed description thereof.

The improved catalysts of the invention are obtained by combining an aluminum halide, such as, for example, aluminum chloride with a halide salt of a cyclic nitrogen base containing the nitrogen atom within the ring, such as, for example, a halide salt of pyridine, pyrollidine, quinoline, alkyl derivatives thereof, etc. Of the halide salts of the cyclic nitrogen bases the chlorides are generally preferred. The catalysts of the inventionare not necessarily limited, however, to those containing only chloride salts, and a halide of aluminum other than aluminum chloride, such as, for example, aluminum bromide may constitute a part or all of the aluminum halide component of the catalyst. Similarly, halide, salts of the cyclic nitrogen bases other than the chlorides may comprise a part or all of the component consisting of the halide salt of a nitrogen base. The proportions of the components in the catalysts may vary within the scope of the invention in accordance with the particular characteristics of the catalyst desired, operating conditions at which they are to be employed, the

nature of the material to be treated, and the like. The degree of catalytic activity, as well as other properties of the catalysts affecting their efficient use under particular operating conditions,

are however, dependent upon their composition.

Since the aluminum halides react with the halide salt of the cyclic nitrogen bases, it is sometimes preferred, and for certain reactions essential, that the aluminum halide be present in molecular excess.

A particularly efficient catalystconsists of the admixture of anhydrous aluminum chloride and pyridine hydrochloride. Pyridine hydrochloride itself has a melting point of about 144 C. It has been found that pyridine hydrochloride and aluminum chloride exhibit compound formation; the 1:1 molar addition complex (csHsN-Hcl-AlCla) melting at approximately 120-l25 C. The addition of aluminum chloride to'the mixture above the equimolecular amount results in catalysts particularly suitable for catalyzing hydrocarbon reactions. When utilizing the catalysts in the liquid state the temperature of a particular operation will govern the content of AlCla in the catalyst. Mixtures of aluminum chloride and pridine hydrochloride containing from 50 to 83 percent by weight of AlCls have a maximum melting point of about 150 C., whereas those having an aluminum chloride content of from about 63 to '77 percent by weight have a maximum melting point of only about 80 C. Catalyst mixtures consisting of or approaching the eutectic composition are particularly preferred. The eutectic composition consisting of 66 percent by weight of aluminum chloride and 34 percent by weight of pyridine hydrochloride melts below approximately 40 C. The solutions of aluminum chloride in pridine hydrochloride, however, possess the very attractive feature of being able to undergo super'cooling to an unusual degree, and their melting points are therefore not indicative of the minimum temperature at which they can be used efliciently in the liquid state. Thus, the aluminum chloride-pyridine I hydrochloride catalyst containingabout 66 percent by weight of AlCla, though possessing a melting point of approximately 40 0., can be used efflciently in the liquid state not only at room temperature (20 C.) butat temperature as low as C. a It is apparent from the foregoing that the invention provides aluminum halide catalysts which can be used in the liquid state at lower temperatures than has been possible with the aluminum halide-containing catalysts available 'quent operation to remove I from the products.

Illustrative of reactions to which the catalysts aluminum halide catalysts available heretofore .melt at temperatures substantially in excess of molten salts comprising aluminum chloride have melting points below 100 C., the relatively narrow temperature range between the minimum temperature at which these mixtures can be maintained in the liquid phase and the maximum temperature at which they can be used for the isomerization of saturated hydrocarbons having at least five carbon atoms to the molecule, is generally too small to assure complete freedom from the danger of freezing at least a part of the catalyst within the system, or to enable any substantial variation in catalyst composition. The greater fluidity of the catalysts of the invention at the lower temperatures on the other hand presents a distinct advantage over catalyst mixtures possessing higher viscosities at the temperature or operation since the conversion obtained depends greatly on the contact efliciency which in turn is a direct function of the viscosity of the liquid catalysts. The catalysts of the invention are also free of the salt components more readily soluble in hydrocarbons, so often present in mixed salt catalysts used heretofore, and therefore eliminate the need for a'subsedissolved catalyst of the invention may be applied with particular g by the following examples:

heretofore. The catalysts of the invention are I ence of active aluminum halide catalysts at temperatures as low as 80 C. Such decomposition not onlyresults in considerable loss of the material treated but results in the rapid degradation of the catalyst activity due to the presence of by-products formed. Since a great many of. the

advantage is the low temperature alkylation of organic compounds containing a hydrogen atom replaceable by an alkyl radical, such as, for example, the reaction of a branched chain paraiiin hydrocarbon with a straight chain olefinic hydrocarbon. The efflciency of the catalysts of the invention in catalyzing this reaction is illustrated Example I I Example II Mixtures of propylene and isopentane were treated with a catalyst consisting of 69 per cent by weight of aluminum chloride and 31 per cent by weight of pyridine hydrochloride at temperatures of 25 (2., 15 0., andO? C.;- the catalyst maintaining its liquid state throughout the operations. The composition of the charge and results .obtained are indicated in the following table:

Temperature, C 25 15 0 Peroentisopentane in charge 85 82 Percent isopentano in roduct 61 71.5 -59 Percent octanes in pr ucts-boilingabovoisopentane. L1 31 37 Percent of propylene charged interacting with isopentane to form octanes 45 15 25 The alkylation in the liquid phase with the aid of the catalysts of the invention, utilized in the liquid state, is preferably executed at temperatures not substantially in excess of about 25 C. The invention is, however, not limited to alkylations which are conducted most advantageously atthese low temperatures and where required higher temperatures may be used. A pressure sufliciently high to at least maintain the reactants in the liquid phase is applied. As stated above, alkylation reactions other than those comprising the interaction of a saturated branched chain paranln with a straight chain olefin are comprised within the scope of the invention. 'Alkylating reactions to which the catalyst may be advantageously applied comprise the interaction of cycloparaiiins with olefinic hydrocarbons, saturated straight chain hydrocarbons withdioleflns, aromatic hydrocarbons with straight chain oleflns, phenols with dioleflns, and the like.

Illustrative of other processes to which the catalysts of the invention may be applied with advantage in the liquid state at relatively low temperatures are the treating or refining operations wherein hydrocarbons or hydrocarbon mixtures are subjected to contact with a liquid-treating agent. A particular application is their use in the treatment of lubricating oils or lubricating oil-containing fractions to effect theremoval of impurities therefrom. The lubricating oils or lubricating oil fractions and the catalysts in the liquid state maybe contacted in concurrent or countercurrent flow for a time sufiiciently long to effect the desired purification and improvement of the'lubricating oil, whereupon the catalyst and hydrocarbons are separated and the catalyst optionally recycled to the treating zone.

It is to be understood that the above examples are but a few of the many reactions conducted at relatively low temperatures in which the catalysts of the invention can be applied with advantage in the liquid state, and that the application of the novel catalysts is not limited thereto.

Though the catalysts of the invention can be applied with particular advantage to processes tions and the nature of the reaction. Thus, the ability of the catalysts to catalyze hydrocarbon reactions, such as, for example, isomerization and alkylation, is generally enhanced by the presence of a hydrogen halide, such as, for example, hydrogen chloride, or compounds capable of liberating a hydrogen halide under the reaction conditions. In the execution of hydrocarbon reactions wherein hydrocarbon decomposition is undesired, materials capabl of suppressing rich side reactions as, for example, hydrogen, may be introduced into the reaction zone.

The catalysts of the invention lend themselves to eflicient application in processes conducted batchwise, intermittently, or in a continuous manner. It is to be pointed out, however, that the nature of the catalysts renders them particularly advantageous to utilization in continuous processes, comprising, for example, the utilization of externally heated, elongated reaction zones of restricted cross-sectional areas through which the catalyst and reactants are passed in concurrent'flow. Emuence from such reaction zones may be passed to a separating zone, wherein the catalyst may be separated readily from the reactants and optionally recycled to the reaction zone.

executed in the liquid phase at relatively low temperatures, their application is not necessarily limited thereto. The catalysts of the invention may also be utilized in the fluid state as catalysts in catalytic processes involving the execution of reactions at higher temperatures and wherein the reactants may optionally be in the'vapor phase. Thus, the fluid catalysts of the invention may be applied to such processes conducted at higher temperatures as those comprising, for example, the degradation of hydrocarbons; conversion of higher boiling hydrocarbons into lower boiling hydrocarbons; polymerization'of normally gaseous olefinic hydrocarbons; isomerization of the less readily degraded hydrocarbons, such as, for example, butane; hydrocarbon reversion operations wherein normally liquid hydrocarbons are contacted withthe catalyst in thepresence of lower boiling, preferably gaseous hydrocarbons, whereby interaction of the lower boiling and higher boiling. hydrocarbons is brought about simultaneously with conversion reactions the specific nature of which reactions are dependent upon the operating conditions used; chlorination of hydrocarbons, etc.

The catalysts of the invention may be utilized in the presence of suitable promoting agents which may vary in nature and in amounts used in accordance with particular operating condiinvention.

The marked advantages of the catalysts of the invention in the liquid state over aluminum halide-containing catalysts available heretofore has been stressed. It is to be pointed out, however, that the novel catalysts in the solid state, as well as their use in catalytic process, are not to be considered beyond the scope of the presentv The catalysts in the solid state may be deposited upon any suitable support material comprising, for example, aluminum oxide, magnesium oxide, bauxite, kieselguhr, silica, silica gel, pumice, majolica chips, carbon, adsorbent claps, or support materials. The support materials may be subjected to the activating treatments well known in the art prior to being impregnated with the aluminum halide catalysts. The solid catalysts may, furthermore, be modified by the presence of other'salts comprising, for ex,- ample, the halides of the alkali or alkaline earth metals.

This application is a division of co-pending application Serial No. 459,326 filed September 22, 1942.

We claim as our invention:

1. An alkylation process which comprises contacting an alkylatable organic compound containing a hydrogen atom capable of replacement by an alkyl group and an alkylating agent at a temperature not substantially in excess of about 25 C. with a molten catalyst comprising aluminum chloride and pyridine hydrochloride, said catalyst containing about 66% by weight of aluminum chloride.

2. An alkylation process which comprises contacting isobutane and propylene at a temperature not substantially in excess of about 25 C. with a catalyst consisting of a molten mixture of aluminum chloride and pyridine hydrochloride, said mixture containing from about 63 to about 72% by weight of aluminum chloride.

3. An alkylation process which comprises contacting a saturated branched chain paraflln hydrocarbon and a straight chain 'olefin at a temperature not substantially in execess of about 25 C. with a catalyst consisting of a molten mixture of aluminum chloride and pyridine about 63 to .about 72% by weight of aluminum chloride.

4. An alkylation' process which comprises contacting an alkylatable organic compound containing a hydrogen atom capable of replacement by' an alkyl group and an alkylating agent at alkylating conditions with a catalyst comprising a molten mixture of aluminum chloride and from about 63 to about 72% by weight of aluminum chloride. r

' pyridine hydrochloride, said mixture containing 5. 'An alkylation process which comprises con:

tacting an alkylatable organic compound containing a hydrogen atom capable of replacement by an alkyl group and an alkylating agent at alkylating conditions with a catalyst comprising an admixture of aluminum chloride and pyridine hydrochloride, said catalyst containing a molecular excess of aluminum chloride.

6. An alkylation process which comprises contacting an alkylatable organic compound containing a hydrogen atom capable of replacement by an alkyl group and an alkylating agent at alkylating conditions with a catalyst comprising a-molten mixture of an aluminum halide and pyridine hydrochloride, said mixture containing the aluminum halide in molecular excess.

' 7. An alkylation process which comprises contacting an alkylatable organic compound containing a hydrogen atom capable of replacement by an alkyl group and an alkylating agent at alkylating conditions with a catalyst comprising a molten mixture of an aluminum halide and the salt of pyridinand a hydrogen halide, said mixture containing the aluminum halide in molecular excess.

8. An alkylation process which comprises con tacting an alkylatable organic compound conasszou.

taining a hydrogen atom capable of replacement by an alkyl group and an alkylating agent at alkylating conditions with a catalyst comprising an aluminum halide in admixture with pyridine hydrochloride, said catalyst containing the aluminum halide in molecular excess.

9. An alkylation process which comprises contacting an alkylatable organic compound containing a hydrogen atom capable of replacement by an ,alkyl group and an alkylating agent at alkylating conditions with a catalyst comprising an aluminum halide in admixture with a halide salt of a cyclic nitrogen base, said catalyst containing the aluminum halide in molecular excess.

10. An alkylation process .which comprises contacting an alkylatable organic compound containing a hydrogen atom capable of replacement by an alkyl group and an alkylating agent at alkylating conditions with a catalyst comprising aluminum chloride in admixture with pyridine hydrochloride. v

11. An alkylation process which comprises contacting an alkylatable organic compound containing a hydrogen atom capable or replacepyridine hydrochloride.

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